AB0807 Relapse Incidence According to HLA-B*27 in Patients with Spondyloarthritis in a Specialized Center in Colombia
Authors: O. J. Felipe Díaz, W. G. Rojas Zuleta, C. Orozco-González, A. E. Pantoja Marquez, C. Ceron, C. L. Giraldo Herrera, M. M. Barbosa-Rengifo, C. Becerra-Arias, J. H. Donado Gómez, N. Duque Zapata
Journal: Annals of the Rheumatic Diseases (2022)

Background Spondyloarthritis (SpA) is a group of inflamatory diseases with multiple clinical manifestations (axial, peripheral, skin, eye, and intestine) including ankylosing spondylitis (AS), reactive arthritis, psoriatic arthritis (PsA), arthritis associated with inflammatory bowel disease, and non-radiographic axial spondyloarthritis. SpA is genetically related to HLA-B*27 as more tan 95% of the cases have it, while in general population its frequency is below 10%. The etiology and pathogenesis of this disease are unknown. Notwithstanding, the misfolding hypothesis suggests that it may be triggered by the formation of HLA-B*27 homodimers. The risk of developing SpA is 5-7% in positive HLA-B*27 individuals (1,2). Objectives Explore the relapse incidence and its associations with HLA-B*27 in SpA patients. Methods SpA patient cohort in a specialized multicentric health institution in Colombia (November 2011 to June 2021). Relapse was defined as the BASDAI increment ≥1 + 2≤ final BASDAI ≤4. A stratified analysis was performed for HLA-B*27 between diagnosis, current medication, and relapse. For group comparisons χ 2 and Wilcoxon tests were used, according to variable distribution. A logistic regression model was run in order to explain relapse incidence. Results 515 patients were included, among whom 60.9% were HLA-B*27 positive. 87.0% had an AS diagnosis (53.3% of men), 11.4% (64.4% of women) non-radiographic axial spondyloarthritis and 1.55% PsA (62.5% of women). Table 1 shows demographic and clinical characteristics. The relapse incidence was associated with positive HLA (Odss Ratio-OR 2.14 CI95% 0.982-4.674, p=0.055) and with time of disease evolution (OR 1.05 IC95% 1.02-1.091, p= 0.001) adjusting for sex. Table 1. Demographic and clinical characteristics HLA-B*27 p value* Negative (n=201) Positive (n=314) Characteristics Median IQR Median IQR Age 49 40 to 58 46 37 to 55 0.020 Time of disease evolution 6.6 4.6 to 10.6 8.6 5.6 to 14.6 0.000 Treatment time 3.2 2.1 to 6.4 3.3 2 to 5.6 0.648 BASDAI at entry 4.10 1.1 to 6.5 4.20 1.6 to 6.3 0.510 Current BASDAI 1.2 0 to 3.3 0.4 0 to 2.0 0.113 n % n % Sex Women 133 66.17 119 37.9 0.000 Men 68 33.83 195 62.1 Diagnosis Non-radiographic axial spondyloarthritis 32 15.92 27 8.6 0.013 Psoriatic arthritis 5 2.49 3 0.96 Ankylosing spondylitis 164 81.59 284 90.45 Current medication Synthetic DMARD 13 6.47 19 6.05 0.780 Anti-TNF 154 76.62 251 79.94 Anti-IL17 24 11.94 29 9.24 Without treatment 10 4.98 15 4.78 Relapse Yes 10 4.98 31 9.87 0.045 * p value for the difference between HLA-B*27 positive and negative groups. IQR: interquartile range Conclusion In SpA patients, HLA-B*27 frequency is higher in AS patients compared to other SpA forms. Furthermore, this is associated with a higher relapse risk and longer time of disease evolution. References [1]Sharip A, Kunz J. Understanding the Pathogenesis of Spondyloarthritis. Biomolecules. 2020 Oct 20;10(10):1461. [2]Colbert RA, Navid F, Gill T. The role of HLA-B*27 in spondyloarthritis. Best Pract Res Clin Rheumatol. 2017 Dec;31(6):797-815. Disclosure of Interests None declared